The "top console user" is designed to let you quickly link assets to their owners. However, I could see how sometimes you might want to use the last logged in user for an asset relation. I added this request to our customer wish list.
This would be terrific. The last logged-on user is many times the owner or primary user of an asset, and it would be great if there were a little button that allowed you to quickly set last user as "owner of" or "user of" the asset.
That's not what I mean, what I want is to see a button that would be beside the last user's name when looking at the asset summary and there you could define a relation between current asset and last user.
I presume that you are referring to the Assets tab where you want to be able to easily add a relation to an asset. This is currently already possible. If you select an asset (or multiple assets) you can click on the Add Relations button on the left-hand pane of the page as seen in the screenshot below. More information on linking assets to other assets or users can be found in this knowledge base article.